Teach set_property and get_property an "INSTALL" property type to be
associated with install-tree file paths. Make the properties available
to CPack for use during packaging. Add a "prop_inst" Sphinx domain
object type for documentation of such properties.
set_property() has APPEND, which creates a list. E.g. when
appending to COMPILE_FLAGS a string is needed, not a list.
With the APPEND_STRING option the value is append as string,
not as list.
Alex
This converts the CMake license to a pure 3-clause OSI-approved BSD
License. We drop the previous license clause requiring modified
versions to be plainly marked. We also update the CMake copyright to
cover the full development time range.